Our 1990 Honda Civic has been running great. We have to smog it in order to get the license renewed for the year. We took the car to the smog station and when the guy started his smogging procedure he told us that the car failed. We had driven the car without the check engine light coming on all year and when the smog guy started testing the car the check engine light came on. His guess was that the oxygen sensor wasn't working and suggested that we change it out. We went and bought a new one and installed it. Back to the smog station we went and we still failed. Now the check engine light is coming on full time. We looked at the computer and counted one red flash followed by 6 red flashes. We have 2 computers so we took out the existing computer and replaced with the extra one. This computer is giving us the check engine light with 5 red flashes. Does anybody know what these flashes mean? Thanks.

 

1: Oxygen Sensor "A" (Primary)
defective circuit or unplugged / defective sensor

2: Oxygen Sensor "B"
defective circuit or unplugged / defective sensor

3: MAP Sensor (Manifold Absolute Pressure)
defective circuit or unplugged / defective sensor

4: CKP Sensor (Crankshaft Position Sensor)
defective circuit or unplugged / defective sensor

5: MAP Sensor (Manifold Absolute Pressure)
mechanical problem / disconnected piping

6: ECT Sensor (Engine Coolant Temperature)
defective circuit or unplugged / defective sensor

7: TPS (Throttle Position Sensor)
defective circuit or unplugged / defective sensor

8: TDC Sensor (Top Dead Center)
defective circuit or unplugged / defective sensor

9: CYP Sensor (Cylinder #1 Position)
defective circuit or unplugged / defective sensor

10: IAT Sensor (Intake Air Temperature)
defective circuit or unplugged / defective sensor

12: EGR Lift Sensor (Exhaust Gas Recirculation)
check the hoses, the EGR valve lift sensor and the System EGR valve.

13: BARO Sensor (Atmospheric Pressure)
defective circuit or unplugged / defective sensor

14: IAC Valve (Idle Air Control)
defective circuit or unplugged / defective sensor

15: Ignition Output Signal
missing or defective ignition output signal

16: Fuel Injector System
defective circuit or unplugged / defective fuel injector

17: VSS (Vehicle Speed Sensor)
defective circuit or unplugged / defective sensor

19: Automatic Transmission Lock Up Control Solenoid Valve
defective circuit or unplugged / defective solenoid valve

20: Electrical Load Detector
defective circuit or unplugged / defective sensor

21: VTEC Solenoid Valve
defective circuit or unplugged / defective solenoid valve

22: VTEC Oil Pressure Switch
defective circuit or unplugged / defective oil pressure switch

23: KS (Knock Sensor)
defective circuit or unplugged / defective sensor

30: Automatic Transmission Signal: "A" / SEAF / SEFA / TMA or TMB
defective circuit or unplugged / defective sensor

31: Automatic Transmission Signal "B"
defective circuit or unplugged / defective sensor

41: Primary Oxygen Sensor - Heater
check the heater for the proper voltage signal.

43: Fuel Supply System
check the fuel pressure, fuel pressure regulator. check the oxygen sensor. also, check for vacuum leaks.

45: System Too Lean or Too Rich
malfunction in the fuel monitoring systems

48: LAF Sensor (Lean Air Fuel)
defective circuit or unplugged / defective sensor

54: CKF Sensor (Crankshaft Speed Fluctuation)
defective circuit or unplugged / defective sensor

58: TDC Sensor 2 (Top Dead Center)
defective circuit or unplugged / defective sensor

61: Oxygen Sensor, Heated - Sensor 1 (Primary)
high voltage, low voltage, or slow response

63: Oxygen Sensor, Heated - Sensor 2 (Secondary)
high voltage, low voltage, or slow response

65: Oxygen Sensor Heater (Secondary)
malfunctioning or defective oxygen sensor heater

67: Catalyst system Efficiency Below Threshold
malfunctioning or defective catalyst system

70: Automatic Transmission
malfunction with the automatic transmission controls

71: Cylinder 1 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

72: Cylinder 2 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

73: Cylinder 3 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

74: Cylinder 4 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

75: Cylinder 5 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

76: Cylinder 6 Misfire or a Random Misfire
a condition is present that is creating a cylinder misfire

80: Exhaust Gas Recirculation
insufficient flow detected

86: ECT Sensor (Engine Coolant Temperature)
circuit range / performance problem

90: Evaporative Emission Control System
leak detected in the fuel tank area

91: Fuel Tank Pressure Sensor
low input

92: Evaporative Emission Control System
insufficient purge flow

 

The problem is almost never the ECU computer itself.

Check that all the sensors are plugged in securely. Check the ground wires on the thermostat housing.

The MAP sensor is mounted on the firewall and connected to the intake by a hose. If the hose is bad or disconnected you will get a code 5.

Whenever you have more than one code, reset the ECU and see which code reoccurs first.

 

Try to use original O2 sensors, for some reason Honda engine are temperamental with aftermarket sensors.